Apparatus for examining and localizing tumors using ultra sounds, comprising a device for localized hyperthermia treatment

ABSTRACT

A hyperthermia treatment apparatus combining a generator of a focused ultrasonic beam comprising a main high frequency electric wave emitter and a main piezoelectric transducer whose active surface is focusing, with an echography device comprising an auxiliary high frequency electric pulse generator associated with an auxiliary piezoelectric transducer and means for causing the zone to be treated to be swept by the ultrasonic examination beam generated by said auxiliary transducer; and with switching and adjustment means for causing, during a main treatment and checking operating mode, emission of said focused beam by said main transducer energized by said main emitter during periodic time intervals separated by shorter time intervals during which the emission of the examination beam and the formation of echographic images are effected.

This is a division of Ser. No. 352,516 filed May 16, 1989 which is adivision of Ser. No. 037,369 filed Apr. 13, 1987, abandoned, which is adivision of Ser. No. 728,905 filed Apr. 30, 1985 which is U.S. Pat. No.4,658,828, which is a continuation-in-part of Ser. No. 674,889 filedNov. 26, 1984 now U.S. Pat. No. 4,617,931.

BACKGROUND OF THE INVENTION

Conventional echography apparatus are obviously used for examiningtumours inside the body by forming an image thereof on the screen of acathode ray tube.

As is known, it is also possible to obtain destruction of the cells--inparticular malignant cells--by subjecting them to a more or lessextended temperature rise. The cells to be destroyed must for example bebrought to about 45° C. in a well controlled way while avoiding reachingexcessive temperatures which could cause serious burns around thelesion. The technical problem to be resolved consists then both incontrolling the amount of energy and the localization thereof.

With the different prior processes (use of ultrahigh frequencies,infrared radiation, and others) superficial tumours can be treated butdeeper tissues cannot be reached.

The invention proposes applying ultra scunds to the examination andhyperthermia treatment and provides an apparatus which combines thethree functions of localizing the zone to be treated, of treating byraising the temperature in a well controlled way in a well definedrestricted region within this zone and simultaneously checking theresults of the treatment.

SUMMARY OF THE INVENTION

The hyperthermia treatment apparatus of the invention combines agenerator of a focused ultra sonic beam comprising a main high frequencyelectric wave emitter and a main piezoelectric transducer whose activesurface is focusing, with an echography device comprising an auxiliaryhigh frequency electric pulse generator associated with an auxiliarypiezoelectric transducer and with means for causing the zone to betreated to be swept by the ultrasonic examination beam being generatedby the auxiliary transducer; and with switching and adjusting means forcausing, during main treatment and checking operation, the emission ofsaid focused beam by the main transducer energized by the main emitterduring periodic time intervals separated by shorter time intervalsduring which the emission of the examination beam and the formation ofechographic images are carried out.

The apparatus advantageously comprises a first auxiliary locatingoperation mode during which only the periodic emission of theexamination beam by the auxiliary transducer is effected and preferablya second auxiliary operating mode for checking the focal region, duringwhich only the periodic emission of the focused beam is effected, butthe main emitter is synchronized by the synchronization circuit of theauxiliary generator for echographic operation, the time intervals whichseparate the successive emission periods during the two auxiliaryoperation modes being substantially smaller than the intervals whichseparate the periods of emission of the focused beam during the mainmode.

It follows from the foregoing that, during the auxiliary operating modesfor obtaining accurate adjustments, the quality of the echographicimage, either of the zone to be treated (locating mode) or of the focalregion (mode for checking the restricted region), will be substantiallybetter than during the treatment mode, during which the successiveimages of the zone to be treated will follow each other for example atintervals of the order of a second, which however allow the position ofthe focal region to be checked satisfactorily during treatment.

In a preferred embodiment, the auxiliary transducer is fixed to thespherical surface of the main transducer and thus, during movement ofthis latter for bringing the focal spot into successive restrictedregions of the tumour, the auxiliary transducer will at all times supplyan image of the treated region and of the zone which surrounds it, thusallowing a permanent check of the treatment to be effected easily andaccurately.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will be clear from thefollowing description.

In the accompanying drawings:

FIG. 1 is the general diagram of a hyperthermia apparatus according to apreferred embodiment of the invention;

FIG. 2 shows schematically in perspective the main transducer and itsmobile support device;

FIG. 3 shows the wave forms at different points of the circuits of theapparatus; and

FIG. 4 illustrates the image obtained on the display screen which theapparatus comprises.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 2 is shown a main transducer 1 in the form of spherical skullcap supported by a mount which allows it to move along three orthogonalaxes X, Y and Z. This mount has been shown schematically, itsconstruction being within the scope of a man skilled in the art. Alongthe axis of the spherical skull cap is disposed an auxiliary transducer2 of a generally cylindrical shape which passes through skull cap 1 andis fixed thereto. A pocket of water P is placed between the skull cap 1and the surface S of the body of the patient, who is assumed lying flaton a horizontal plane.

The skull cap 1 has for example a diameter of 200 to 300 mm and isformed from a large number (300 or 400) of piezoelectric elements 10,11, etc . . . (FIG. 1) isolated from each other and juxtaposed so as toform a mosaic. These elements are metallized on both faces, one of themetallizations being connected to ground and the other to connectionsfor energization by a main emitter 3.

This latter delivers an electric signal A (FIG. 3) formed of highfrequency wave trains (500 KHz for example) of a relatively low peakpower (about 10 or a 100 watts for example), but of a relatively longduration (for example of the order of a second) separated by timeintervals of the order of 1/10 second, the time required for theechography device to form an image. It is then a question of operatingconditions using substantially continuous emission for the treatment.Such operating conditions may be obtained by means of emitters usingpower transistors. Preferably, the elements of transducer 1 will bedivided up into groups each energized by a separate emitter (rectangle 4symbolizing the assembly of these emitters), the elements of each groupbeing spaced apart in the same circular zone of the spherical surface.By adjusting the relative phases of the emissions, it is possible tomodify the energy distribution in the focusing region of the ultra sonicbeam.

An input 31 to emitter 3 symbolizes an adjustment of the emitted powerand an input 32 symbolizes an adjustment of the wave train duration. Thefocal spot formed in the center F of the sphere may, with thistechnique, be very small (diameter of 2 or 3 mm for example) and have aposition which is strictly fixed for a given position of the transducer.

In FIG. 1 it can be seen that the auxiliary transducer 2 is itselfconnected both to a high frequency electric pulse emitter 21 and to areception amplifier 22 followed by an analog-digital converter 23,itself followed by a memory 24. Emitter 21 is synchronized by a pulsegenerator 211 which delivers 256 pulses during each of the successivetime intervals of 1/10 second. To each of these time intervalscorresponds a complete sweep of a given angular sector θ (FIG. 1) by thebeam emitted by transducer 2 so the formation, in the sweep plane, of animage of the zone observed by the echography device.

Transducer 2 is advantageously of the type described in French patentapplications number 80 16717 filed on the Jul. 29, 1980 for: "Asectorial sweep echography probe comprising two coupling liquids", andno. 80 16718 filed on the Jul. 29, 1980 for: "Mechanical sectorial sweepechography probe", that is to say that it comprises an oscillatingpiezoelectric element 200 controlled by a motor 201, itself controlledby an electronic circuit which is shown symbolically by a rectangle 4.This electronic circuit provides control signals for the motor 201housed inside the case of the transducer 2 and is adapted so that acomplete oscillation of the motor corresponds to the above definedduration for forming an image (1/10 sec.).

In a first operating mode (treatment and checking) switch 210 is inposition I as well as switches 212 and 33.

In position I of switches 33 and 212, generator 211 is synchronized by afirst output 41 of circuit 4, and this latter is then adjusted, by meansnot shown, for generating at its output 43 connected to motor 201signals having the wave form (MT) shown in FIG. 4. An image is sweptthen in 1/10 sec. and is followed by a time interval of 1 sec. duringwhich the oscillating element 200 remains immobile, so that transducer 2receives no echos.

During the intervals between the sweep periods, a circuit 34 generatessquare waves of 1 sec. which serve for synchronizing emitter 3 whereas,during the sweep periods, a circuit 213 generates square waves of 1/10sec. which serve for synchronizing the generator 211.

Thus, in this operating mode, transducer 1 generates an ultra-sonic beamunder substantially continuous operating conditions whereas theechography device forms an image every second in the intervals betweenthe wave trains. At (BT) has been shown the wave forms of the signalsthen emitted by generator 211.

In a second operating mode (locating) with switch 210 in position I,switch 33 is in position II, so that emitter 3 is not synchronized andthe focused ultrasonic beam is not emitted. Switch 212 is also inposition II so that generator 211 is synchronized by a second output 42of circuit 4 and this latter is adjusted so as to generate at its output43 signals having the wave forms (MR) shown in FIG. 3. The 1/10 sec.sweeps are then separated by time intervals of 1/100 sec. only and theimages are formed from echos coming from the reflection of the pulsesgenerated by transducer 2. Generator 211 delivers the signals (BR).

In a third operating mode (checking the focal region), switch 210 is inposition III, so that the emitter 21 and transducer 2 do not emit.Switch 212 is again in position II so that generator 211 is synchronizedby the output 42 of circuit 4 and this latter is adjusted as in thesecond operating mode so that the 1/10 sec. sweeps are again separatedby intervals of 1/100 sec. Switch 33 is in position III and consequentlyemitter 3 is now synchronized by the generator 211 which then deliversthe signals (BR).

In this third operating mode, the echographic device is thereforeformedby emitter 3, transducer 1 operating for emission and transducer 2operating for reception. The result is that an image of the zone ofconcentration in the focal region of the energy emitted by thetransducer 1 is obtained.

The echographic signals received at 22 in the first or third operatingmodes are, after analog-digital conversion at 23, stored line by line inmemory 24, a writing addressing device 25, controlled by circuit 4,causing the respective deflection angles of the beam emitted and/orreceived by transducer 2 to correspond with the respective lines of thememory. A device 26 for rapid reading of the memory energizes the X andY deflection coils of a cathode ray tube 28, so the brightness controlelectrode receives the corresponding contents from memory 24,transformed into an analog signal by a digital-analog converter 27.

The practical construction of all the circuits described and shown iswithin the scope of a man skilled in the art. The control circuit 4 mayfor example comprise a one shot multivibrator delivering square waves ofa duration adjustable to 1/100 s or 1 s depending on the operating modeand circuits for generating increasing and decreasing voltages of a 1/10s duration, triggered off by said square waves.

The apparatus which has just been described operates as follows:

In the locating operating mode, the operator searches for and localizesthe zone to be treated. The display device is adapted, in a way knownper se, so as to materialize on the screen of the cathode ray tube (forexample by means of a cross) the theoretical position of the focal spotin the sectional plane shown, which plane passes through the axis ofsymmetry of transducer 1. (It is a question of B type echography). Theoperator begins by moving transducer 1 along X, until the tumour appearsclearly on the screen, then he moves it along Y and Z, until the crosscoincides with the central region of the image of the tumour (K, FIG.4). At this moment, the switches may be placed in position for checkingthe focal region: only this latter is then made visible on the screen,with a luminosity proportional to the corresponding energyconcentration. Thus a representation is obtained of what thedistribution of the energy of the treatment wave will be, which allowsthe adjustments to be checked and perfected.

During treatment, the apparatus only supplies one image per second, butthis rate is sufficient for substantially permanently checking theposition of the focal spot.

It is clear that the apparatus described allows the evolution of thetumour to be checked after each treatment sequence. It is evident thatdifferent modifications may be made thereto and even according to otherembodiments, without departing from the scope and spirit of theinvention.

What is claimed is:
 1. An article of manufacture comprising:(a) aconcave focusing treatment wave transducer assembly for treating atarget and a plurality of mounted juxtaposed piezoelectric elements, and(b) separate target locating and treatment aiming ultrasound transducermeans adapted to be positioned between a focal point of said treatmentwave transducer assembly and said target for scanning said target withechographic ultrasound and for generating a target image; (c) meansdisplaying said image of said target; (d) means displaying a visibleindication of said focal point of said treatment wave transducerassembly; and (e) means bringing said image and said indication intocoincidence.
 2. An article as set forth in claim 1 wherein said elementsare juxtaposed in a mosaic.
 3. An article as set forth in claim 1wherein said locating and aiming transducer means is within thetreatment transducer volume.
 4. An article of manufacture comprising:(a)a piezoelectric treatment wave transducer; (b) concave treatment wavefocusing means for focusing said transducer at a focal point; and (c)separate target locating and treatment aiming means adapted to bepositioned between said focal point and said treatment wave transducerfor scanning a target and for generating an image of said target; (d)means displaying said image; (e) means displaying a visible indicationof said focal point of said focusing means; and (f) means bringing saidimage and said indication into coincidence.
 5. An article as set forthin claim 4 wherein said treatment wave transducer includes a pluralityof piezoelectric elements juxtaposed in a mosaic.
 6. An article as setforth in claim 4 wherein said locating and treatment aiming means ispositioned within the volume defined by said concave focusing means. 7.A concave focusing treatment wave article comprising:(a) treatment wavefocusing means for focusing treatment waves at a human body target; (b)separate target locating and treatment wave aiming means for scanningand generating an image of said target, adapted to be positioned betweensaid target and said focusing means; and (c) means displaying a realtime image of said target in coincidence with a visible indication of afocal point of said focusing means.
 8. A concave focusing treatment wavearticle comprising:(a) treatment wave focusing means for aiming saidarticle at a focal point; and (b) separate target locating and treatmentwave aiming means adapted to be positioned between said focal point andsaid focusing means for scanning and generating an image of said target;and (c) means for displaying said image of said target in coincidencewith a visible indication of a focal point of said treatment wavefocusing means.
 9. An article of manufacture comprising:(a) a concavecomponent comprising means focusing treatment waves along a treatmentwave path at a focal point and a treatment wave transducer having aplurality of piezoelectric elements mounted thereagainst, and (b)locating and aiming device means comprising a separate target locatingand treatment wave aiming ultrasound transducer adapted to be positionedbetween a focal point of said component and a target and a device forscanning and generating an image of a treatment target with echographicultrasound and means for displaying an image of said target incoincidence with a visible indication of said focal point of saidconcave component.
 10. An article as set forth in claim 9 wherein saidelements are juxtaposed in a mosaic.
 11. An article as set forth inclaim 9 wherein said locating and aiming transducer is mounted in asupport sleeve which extends within the concave component volume.
 12. Anarticle of manufacture comprising:(a) a piezoelectric treatment wavetransducer having juxtaposed piezoelectric elements and concavetreatment wave focusing means for focusing treatment waves at a target;and (b) separate human body target locating and treatment aiming meansadapted to be positioned between a treatment target and saidpiezoelectric elements for scanning and generating an image of saidtarget and means for displaying an image of said target in coincidencewith a visible indication of a focal point of said focusing means. 13.An article as set forth in claim 12 wherein said treatment wavetransducer includes a plurality of piezoelectric elements juxtaposed ina mosaic.
 14. An article as set forth in claim 12 wherein said locatingand treatment aiming means are positioned in a support sleeve which isat least partly within said concave focusing means.